1. Technical Field
This disclosure relates to electronic assemblies and to methods of making electronics assemblies. More particularly, the disclosure relates to optoelectronics assemblies which may include a light source and a light sensor, and to methods of making optoelectronics assemblies.
2. Discussion of the Related Art
Various electronics packaging techniques are utilized to achieve miniaturization, environmental protection and high performance. In one example known as a Wafer Level Package (WLP), multiple semiconductor die are encapsulated in a molded material known as a reconstructed wafer. One or more interconnect layers and a ball grid array may be added to the reconstructed wafer. The reconstructed wafer is then divided into individual electronics assemblies, each of which may be mounted in electronics equipment and electrically connected via the ball grid array.
In some applications, the wafer level packaging technique may be utilized for making an electronics assembly including optical elements, such as a light source and a light sensor. One example is an optical proximity sensor where a light beam is transmitted by the proximity sensor. An object in the path of the light beam reflects the light beam to the light sensor. A change in light level detected by the sensor indicates the presence of the object. In such an electronics assembly, the light source and the light sensor are mounted in separate chambers so that the light sensor detects the light reflected from the object but does not detect light from the light source itself.
It is commonplace in semiconductor processing to form a passivation layer on the top surface of a semiconductor die package. The passivation layer is transparent. If the semiconductor die is positioned below both chambers of the optoelectronics assembly, the passivation layer may provide a path for undesired optical crosstalk between chambers. Such crosstalk may cause the optoelectronics assembly to provide erroneous results. In particular, light from the light source may leak into the light sensor chamber and be detected. Accordingly, there is a need for improved electronics assemblies and methods of making electronics assemblies.